Hitherto, there has been known a weather detection system composed of a vehicle and a navigation server (for example, refer to Patent document 1).
In the weather detection system, a sensor for detecting probe information and weather data is disposed in the vehicle, and the detected probe information and the detected weather data are sent to the navigation server via a navigation device. In the navigation server, the weather conditions of an area where the vehicle is present are detected on the basis of the received probe information and the received weather data.